How to practice Python when you can't write code despite understanding tutorials

Feb 19, 2026

Cowrie

Dev @ Bswen

Problem

I watched 20 hours of Python tutorials. I understood every concept. Variables? Got it. Loops? Easy. Functions? Makes sense.

But when I opened a blank text editor to write my first program, I froze.

I stared at the blinking cursor for 10 minutes. I couldn’t even write a simple temperature converter without looking up a tutorial.

I felt like I had learned Spanish vocabulary for 6 months but couldn’t order a taco. This is the comprehension-production gap.

Environment

• Python 3.11
• VS Code (but any editor works)
• Zero actual coding experience (only tutorial watching)

What happened?

I spent 2 months “learning” Python by watching tutorials. I could explain what a for loop does, identify a list comprehension, and tell you when to use a dictionary.

Here’s what I understood:

• Variables store data
• Functions organize code
• Loops repeat actions
• Conditionals make decisions

But when I tried to write this simple program:

temperature_converter.py

def fahrenheit_to_celsius(fahrenheit):
    return (fahrenheit - 32) * 5 / 9

def celsius_to_fahrenheit(celsius):
    return (celsius * 9 / 5) + 32

# Add code to get user input and display result

I couldn’t finish it. I didn’t know:

• How to get input from the user
• Whether to use input() or command-line arguments
• How to format the output nicely
• Whether to put this in a main() function or not

The problem? I had passive knowledge (reading) but no active skills (writing).

How to solve it?

I realized tutorials teach you to read code, not write it. So I built a progressive exercise system that bridges this gap through four tiers.

Tier 1: Code Modification (Entry Level)

Instead of writing from scratch, start by modifying working code.

Exercise 1: Temperature Converter Extension

temp_converter.py

def fahrenheit_to_celsius(fahrenheit):
    return (fahrenheit - 32) * 5 / 9

# YOUR TASK: Add the reverse function below
def celsius_to_fahrenheit(celsius):
    # Round to 1 decimal place
    pass  # Replace this with your code

# Test your code
print(fahrenheit_to_celsius(100))  # Should print 37.78
print(celsius_to_felsius(37))      # Should print 98.6

I started with the given function and added:

def celsius_to_fahrenheit(celsius):
    fahrenheit = (celsius * 9 / 5) + 32
    return round(fahrenheit, 1)

It worked. This tiny win built confidence.

Exercise 2: List Operations Extension

list_stats.py

def calculate_stats(numbers):
    total = sum(numbers)
    count = len(numbers)

    # YOUR TASK: Add average and product calculations
    average = None  # Replace None
    product = None  # Replace None

    return {
        'sum': total,
        'count': count,
        'average': average,
        'product': product
    }

# Test
print(calculate_stats([1, 2, 3, 4]))
# Should return: {'sum': 10, 'count': 4, 'average': 2.5, 'product': 24}

I added:

average = total / count if count > 0 else 0

product = 1
for num in numbers:
    product *= num

Exercise 3: String Manipulator Update

string_tools.py

def reverse_string(s):
    return s[::-1]

# YOUR TASK: Add palindrome checker
def is_palindrome(s):
    pass  # Return True if s reads same forwards/backwards

# Test
print(reverse_string("hello"))      # "olleh"
print(is_palindrome("racecar"))     # True
print(is_palindrome("python"))      # False

I wrote:

def is_palindrome(s):
    return s == s[::-1]

After 10 modification exercises, I stopped freezing on blank screens.

Tier 2: Bug Fixing (Beginner)

Now I practice reading code to find errors.

Exercise 4: Loop Counter Fix

buggy_sum.py

def sum_list(numbers):
    total = 0
    for i in range(len(numbers) + 1):  # BUG HERE
        total += numbers[i]
    return total

# Test - This will crash
print(sum_list([1, 2, 3]))

I ran it and got:

IndexError: list index out of range

The problem: range(len(numbers) + 1) goes too far. The list has indices 0, 1, 2, but the loop tries 0, 1, 2, 3.

I fixed it:

for i in range(len(numbers)):  # Removed +1

Exercise 5: Function Return Error

buggy_return.py

def calculate_discount(price, discount_percent):
    discount = price * (discount_percent / 100)
    final_price = price - discount
    # BUG: Missing return statement

# Test
order_total = calculate_discount(100, 20)
print(order_total)  # Prints: None

I realized the function calculated but didn’t return anything. Added:

return final_price

Exercise 6: List Index Error

buggy_filter.py

def get_first_even(numbers):
    for i in range(1, len(numbers)):  # BUG: Starts at wrong index
        if numbers[i] % 2 == 0:
            return numbers[i]
    return None

# Test
print(get_first_even([1, 2, 4, 6]))  # Returns 4, should return 2

I spotted it: The loop starts at index 1, skipping the first element.

Fixed:

for i in range(len(numbers)):  # Start at 0

Tier 3: Code Completion (Intermediate Beginner)

Fill in the blanks of partially-written code.

Exercise 7: Complete the Calculator

calculator.py

def calculate(a, b, operation):
    """
    Perform basic arithmetic operations.

    Args:
        a: First number
        b: Second number
        operation: 'add', 'subtract', 'multiply', or 'divide'

    Returns:
        Result of calculation or None if invalid operation
    """
    # YOUR TASK: Complete this function
    if operation == 'add':
        result = None
    elif operation == 'subtract':
        result = None
    elif operation == 'multiply':
        result = None
    elif operation == 'divide':
        result = None
        # Handle division by zero
    else:
        return None

    return result

# Test
print(calculate(10, 5, 'add'))       # Should print 15
print(calculate(10, 5, 'subtract'))  # Should print 5
print(calculate(10, 5, 'multiply'))  # Should print 50
print(calculate(10, 5, 'divide'))    # Should print 2.0
print(calculate(10, 0, 'divide'))    # Should handle gracefully

I completed it:

def calculate(a, b, operation):
    if operation == 'add':
        result = a + b
    elif operation == 'subtract':
        result = a - b
    elif operation == 'multiply':
        result = a * b
    elif operation == 'divide':
        if b == 0:
            return "Cannot divide by zero"
        result = a / b
    else:
        return None

    return result

Exercise 8: Finish the Filter

list_filter.py

def filter_even_numbers(numbers):
    """
    Return a new list containing only even numbers from input.

    Args:
        numbers: List of integers

    Returns:
        List of even integers
    """
    # YOUR TASK: Complete this using list comprehension
    evens = [num for num in numbers if None]  # Fix the condition

    return evens

# Test
print(filter_even_numbers([1, 2, 3, 4, 5, 6]))  # [2, 4, 6]
print(filter_even_numbers([7, 11, 13]))         # []

I fixed the condition:

evens = [num for num in numbers if num % 2 == 0]

Tier 4: From-Scratch Challenges (Advanced Beginner)

After 3 weeks of tiers 1-3, I started writing code from scratch.

Exercise 9: Password Generator

password_gen.py

import random
import string

def generate_password(length=12):
    """
    Generate a random password with mixed characters.

    Args:
        length: Password length (8-16 characters)

    Returns:
        Random password string
    """
    if length < 8 or length > 16:
        return "Password length must be between 8 and 16"

    # Create character pools
    lowercase = string.ascii_lowercase
    uppercase = string.ascii_uppercase
    digits = string.digits
    special = "!@#$%^&*"

    # Ensure at least one of each type
    password = [
        random.choice(lowercase),
        random.choice(uppercase),
        random.choice(digits),
        random.choice(special)
    ]

    # Fill remaining length
    all_chars = lowercase + uppercase + digits + special
    for _ in range(length - 4):
        password.append(random.choice(all_chars))

    # Shuffle the password
    random.shuffle(password)

    return ''.join(password)

# Test
print(generate_password(8))   # 8-character password
print(generate_password(12))  # 12-character password
print(generate_password(5))   # Error message

I wrote this from scratch after 3 weeks of practice. It took me 20 minutes, not 2 hours like before.

Exercise 10: CLI Quiz App

quiz_app.py

def run_quiz():
    """
    Run a simple command-line quiz with score tracking.
    """
    questions = [
        {
            'question': 'What is the keyword to define a function in Python?',
            'options': ['func', 'def', 'function', 'define'],
            'answer': 'def'
        },
        {
            'question': 'Which data type is immutable?',
            'options': ['list', 'dict', 'tuple', 'set'],
            'answer': 'tuple'
        },
        {
            'question': 'What does len() function return?',
            'options': ['Length of object', 'Type of object', 'Value of object', 'None'],
            'answer': 'Length of object'
        },
        {
            'question': 'How do you start a comment in Python?',
            'options': ['//', '#', '/*', '--'],
            'answer': '#'
        },
        {
            'question': 'What is the output of print(2 ** 3)?',
            'options': ['6', '8', '9', '5'],
            'answer': '8'
        }
    ]

    score = 0
    total = len(questions)

    for i, q in enumerate(questions, 1):
        print(f"\nQuestion {i}: {q['question']}")

        for idx, option in enumerate(q['options'], 1):
            print(f"  {idx}. {option}")

        user_answer = input("Your answer (1-4): ").strip()

        # Check if user entered a number
        if not user_answer.isdigit():
            print("Invalid input! Please enter a number.")
            continue

        answer_index = int(user_answer) - 1

        # Validate range
        if answer_index < 0 or answer_index >= len(q['options']):
            print("Invalid choice! Please try again.")
            continue

        selected_answer = q['options'][answer_index]

        # Check correctness
        if selected_answer == q['answer']:
            print("Correct!")
            score += 1
        else:
            print(f"Wrong! The correct answer is: {q['answer']}")

    # Final score
    percentage = (score / total) * 100
    print(f"\n{'='*40}")
    print(f"Quiz completed!")
    print(f"Your score: {score}/{total} ({percentage:.1f}%)")

    if percentage >= 80:
        print("Excellent work!")
    elif percentage >= 60:
        print("Good job!")
    else:
        print("Keep practicing!")

# Run the quiz
if __name__ == "__main__":
    print("Welcome to the Python Quiz!")
    print("Answer 5 questions to test your knowledge.\n")
    run_quiz()

This took 35 minutes to write. A month ago, I couldn’t have started it.

Where to practice?

I use several platforms depending on my goal:

Platform	Difficulty	Cost	Best For	Link
CodingBat	Beginner	Free	Quick warm-ups (5-10 min)	codingbat.com/python
Edabit	Beginner-Intermediate	Freemium	Bite-sized daily practice	edabit.com/python
Exercism	All levels	Free	Mentor feedback on solutions	exercism.org/python
HackerRank	Beginner-Advanced	Freemium	Structured skill tracks	hackerrank.com/python
LeetCode	Intermediate-Advanced	Free	Algorithm practice	leetcode.com

My daily routine (30 minutes):

• 5 minutes: Review yesterday’s code
• 15 minutes: New exercise at current tier
• 5 minutes: Read the solution (even if I solved it)
• 5 minutes: Write down what I learned in a code journal

My progression timeline

Week 1-2 (Tier 1): Modified 20 code snippets. Still felt slow, but I stopped freezing.

Week 3-4 (Tier 2): Fixed 15 bugs. Started recognizing common patterns (off-by-one errors, missing returns).

Week 5-6 (Tier 3): Completed 10 partial programs. Could write simple functions without looking up syntax.

Week 7+: Writing from scratch (Tier 4). Built password generator, quiz app, and a simple to-do list.

The reason

The comprehension-production gap is normal in language learning, and programming is a language. I had receptive fluency (reading) but no productive fluency (writing).

Cognitive science shows that deliberate practice - focused, progressive exercises with feedback - builds skills 10x faster than passive consumption.

My four-tier system works because:

1. Tier 1 builds confidence through small wins
2. Tier 2 trains pattern recognition (debugging)
3. Tier 3 scaffolds the cognitive load (filling blanks)
4. Tier 4 applies skills to new problems

Summary

In this post, I showed how to bridge the gap between understanding Python tutorials and actually writing code through a four-tier progressive exercise system. The key point is to start with code modification, then bug fixing, then completion, before attempting from-scratch projects.

Start with Tier 1, Exercise 1 right now. Don’t read the rest of this post until you’ve completed it. Seriously - paste that temperature converter code into your editor and add the reverse function. I’ll wait.

Final Words + More Resources

My intention with this article was to help others share my knowledge and experience. If you want to contact me, you can contact by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

• 👨‍💻 CodingBat - Warm-up Python Problems
• 👨‍💻 LeetCode Easy Problems
• 👨‍💻 Exercism - Python Track with Mentor Feedback
• 👨‍💻 HackerRank Python Practice
• 👨‍💻 Edabit - Bite-sized Python Challenges
• 👨‍💻 Python Official Documentation
• 👨‍💻 Anders Ericsson - Deliberate Practice Research
• 👨‍💻 Josh Kaufman - The First 20 Hours
• 👨‍💻 r/learnprogramming

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!

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